Backyard hens’ eggs contain 40 times more lead on average than shop eggs

https://theconversation.com/backyard-hens-eggs-contain-40-times-more-lead-on-average-than-shop-eggs-research-finds-187442

by sohkamyung • 4 years ago

112 111 4 years ago

theconversation.com

tmikaeld2• 4 years ago

Interesting, makes me question if the local farms here the EU are checked for lead amount in the blood.

rob742• 4 years ago

I mean, even local farms are usually in rural areas, where the lead contamination is probably much less than in the inner cities studied by this article. Still, I wonder where the lead originally came from? Old deposits from leaded gasoline fumes? Or does it come from lead paint, lead roofing, lead pipes or similar?

tmikaeld2• 4 years ago

Not sure why I was downvoted, but it doesn't look good in the EU either.

https://europepmc.org/article/MED/30204015

I think it's from paint the chickens pick on, fallen off older farm houses, it wasn't uncommon in the 60-70s.

https://www.familyhandyman.com/list/ways-to-minimize-lead-pa...

sha256sum• 4 years ago

We assessed trace metal contamination in backyard chickens and their eggs from garden soils across 55 Sydney homes. We also explored other possible sources of contamination such as animal drinking water and chicken feed.

I’m not surprised this would be the case with chickens foraging yards in cities. The title should probably reflect that as I doubt this would be the case in a less urban environment.

mauvehaus• 4 years ago

If you have an old farmhouse on your rural property, it's highly likely that it was painted with lead-based paint at some point in its history. Likely many times, in fact. A lot of the soil contamination comes from lead paint flaking off as it weathers. Fortunately(ish), this is mostly confined to the adjacent areas.

Given that you likely have more space in which to free range your chickens, the problem is now reduced to free ranging them away from the house. Arranging this is left as an exercise to the reader :-)

unlikelymordant• 4 years ago

If people have dumped engine oil as a weed suppressant or just poured it out on the ground, youll get a lot of heavy metals including lead.

Also leaded gasoline used to be popular, and would likely have been used for all sorts of things like an accelerant or a degreaser. It doesnt take many incidents like that over 50 years to spread lead all over the place.

cmrdporcupine3• 4 years ago

Even more concerning is that a large # of rural properties are on old apple orchards.

Spraying lead arsenate as a pesticide on apples was a fairly common practice up until the 60s.

It accumulates in the soil and never goes away.

The scale of the problem isn't spoken about much because there's literally nothing that can be done about it.

duxup3• 4 years ago

Also most chicken farms aren’t like some old stereotype with chickens in the yard up to the house.

They are usually far from the house and “old farmhouses” aren’t all that common.

cmroanirgo• 4 years ago

Looking at the maps, the worst levels are in the city centre, not in the suburbs, which is a weird result because it hints at pollution being a cause, but there would be less chickens being raised there than in the suburbs.

raverbashing• 4 years ago

I wonder how much of this is from lead paint around buildings

helsinkiandrew• 4 years ago

I wondered how much the chickens may have been concentrating the lead and if it was significant compared with the extra lead the owners of those chickens are being exposed to from their city home environment.

But this article suggests that air lead pollution is not an issue:

https://www.abc.net.au/news/2017-04-09/lead-pollution-threat...

danjoredd2• 4 years ago

Its almost as if...there is a bias in the media in favor of the egg and gas industry. No...don't raise your own eggs. Buy OUR eggs! They are safer, and don't contain lead like yours! Oh, the lead in the air is more dangerous? No, you are being paranoid.

sudden_dystopia2• 4 years ago

Had me a bit freaked out until I saw that this was due to tainted soil in urban settings. I’m sure there is still lead at lower concentrations pretty much everywhere considering it was in our gasoline for so long. But the title should probably be more like the eggs of free range hens in urban setting contain 40x lead than chickens confined to a tiny box.

causi2• 4 years ago

Had me a bit freaked out until I saw that this was due to tainted soil in urban settings.

While that's true, what they determined to be dangerous levels are still low enough to be in the "zero to low" category for most other classifiers like universities. I wouldn't assume your soil is safe unless you have an actual measurement done.

causi2• 4 years ago

To keep egg lead below 100μg/kg, our modelling of the relationship between lead in soil, chickens and eggs showed soil lead needs to be under 117mg/kg

A good number to remember if you or anyone you know is considering getting chickens.

sudden_dystopia2• 4 years ago

I wonder if this can be remediated by covering the chickens run in a deep layer of mulch and shredded leaves, letting that compost over time as the chickens poop and scratch in it. Over time the layer of contaminated soil could be buried deeper under fresh compost. I also wonder if you could innoculate the wood chips with a fungus whose mycelium could filter out the soil a bit.

ncmncm2• 4 years ago

Chickens scratch, seeking tiny rocks for their crop. If they don't find any in your overlayer, they go deeper.

Pigalowda• 4 years ago

Maybe mix the mulch with some fine gravel

ncmncm2• 4 years ago

Of course this will vary radically from one place to another.

Perhaps most important may turn out to be how much lead paint has flaked off buildings in the area.

nomilk• 4 years ago

Is forty times an extremely small number still negligible? (asking not out of skepticism but curiousness)

mirker• 4 years ago

There isn’t an official safe exposure amount for lead [1].

[1] https://www.who.int/news-room/fact-sheets/detail/lead-poison...

superb-owl• 4 years ago

In the US there is: https://www.cdc.gov/niosh/topics/lead/limits.html

malf• 4 years ago

The little gray snippet (“backyard hens’ eggs…”) at the top of the page is clickable.

Broken_Hippo• 4 years ago

That is always going to depend on the context. Sometimes a small number makes a difference, sometimes not.

40 times greater chance of a comet hitting you on the head? Still gonna be negligible and you probably shouldn't be too concerned.

40 times more lead in your eggs? Well, you should really be aiming for zero lead in your eggs and lead poisoning can happen over time (My cousins got lead poisoning from old plates and bowls). If you have chickens, you are probably being fed a consistent diet of eggs. So yeah, it might very well be a concern.

s1artibartfast2• 4 years ago

You didn't answer the question, you just reiterated that lead is bad.

Is this 40x the chance of getting hit by a comet, or 40 games of Russian roulette.

The study talks about increased blood lead levels ~1 to 1.4 μg/dL. Now how risky is that? The CDC has alert levels for children of 5 ug/dL, recently revised from 10 ug/uL.

What the measurable impact is from 5ug, let alone 1 ug is hotly debated because it is so difficult to asses.

Here is the study they cross reference:

Our IEUBK model predictions suggested that consuming one egg per day with a lead concentration less than 100 μg/kg, in addition to the model’s default lead exposure from diet and all other sources, would result in estimated GM blood-lead concentration increases of less than 1 μg/dL in children. However, daily consumption of one egg with the highest lead concentration we found in eggs from NYC community gardens (167 μg/kg) would increase GM blood-lead concentrations by 1 to 1.4 μg/dL, and daily consumption of one egg with 300 μg/kg lead would increase GM blood-lead concentrations by as much as 2.4 μg/dL, well above the 1 μg/dL guideline.

The IEUBK model output was also used to estimate the number of eggs children could consume without excessively increasing blood-lead concentrations. Among children 1 – 6 years of age, the model output suggested that an increase in dietary lead intake of up to 5.6 μg/day for 1 to 2 year olds (and slightly larger increases – as much as 7.6 μg/day – for older children), would raise GM blood-lead concentrations by less than 1 μg/dL. This intake translates into the consumption of about 6 medium eggs/day at 20 μg/kg lead, 2.5 eggs/day at 50 μg/kg, or 1.2 eggs/day at 100 μg/kg.

These evaluations implied that, overall, the lead concentrations we found in eggs from NYC community gardens were not likely to significantly increase lead exposure or to pose a significant health risk. However, frequent consumption of eggs with the highest lead concentration we found could significantly increase lead exposure, and chickens exposed to higher concentrations of lead in soil are likely to produce eggs with higher concentrations of lead. This exposure pathway could potentially be significant in some gardens, and it should not be ignored

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4037389/

anm89• 4 years ago

All, large cities are filthy, contaminated places. You shouldn't be growing food in random soil you find lying around in them and you shouldn't be raising animals in that soil unless you are carefully managing the sources and exposure of everything.

galangalalgol• 4 years ago

In old neighborhoods in the US (anything over a century is old in the US) you find the craziest things in the soil. The sheer amount of glass and plastic and metal is staggering. Just digging the holes for ornamental plants was enough to make me realize all food gardening would need to be in raised beds with liners and known soil.

In parts of the world with longer periods of habitation (all of them) what do you find in the soil?

rob742• 4 years ago

[in Australian cities]

wolongong942• 4 years ago

Does anybody know whether fruit & vegetables can contain lead if all external matter is 100% removed or peeled off? i.e do plants suck this stuff up? my parents grow fruit and vegges at home and we live next to a road in a fairly old neighborhood..

huffmsa• 4 years ago

Plants don't typically pull lead out of the soil through their roots. Your main concern should be surface contamination from soil getting splashed onto the plant when it's watered / rains

danjoredd2• 4 years ago

This is why one always rinses plants off before consumption.

kaikai• 4 years ago

Sunflowers are known bioaccumulators.

jefftk4• 4 years ago

Here's the standard advice: https://extension.oregonstate.edu/gardening/soil-compost/sho...

If soil lead is sufficiently high, leafy greens and root vegetables are not recommended.

micromacrofoot• 4 years ago

amazing how much damage cars have done in 100 years

rossdavidh• 4 years ago

So, while the impact on eggs is interesting and all, a more appropriate title for the article would be "urban Australia is so lead-polluted that gardening and raising chickens shows lead poisoning". In other words, if the place you're living has so much lead in the soil that it is unsafe to produce food there, it seems unlikely that it is safe to be living there at all.

duxup3• 4 years ago

it seems unlikely that it is safe to be living there at all

Is it?

Just living there you’re not ingesting the soil.

hkt• 4 years ago

In all likelihood it is reaching the soil through the air as particulates.

klyrs4• 4 years ago

you’re not ingesting the soil.

You don't have kids, do you?

giantg28• 4 years ago

Why would it be unsafe to live there at all? The cutoff for crops is typically 400 ppm. That seems like it would be low enough to live there.

boplicity• 4 years ago

There is no level of exposure to lead that is known to be without harmful effects. [1]

Fortunately, plants don't seem to generally absorb lead.[2] It may be in the soil, though, which means you should carefully wash your plants before eating them.

It does seem to be a big deal, though, that chickens absorb lead and that the lead ends up in their eggs. There are many people who have backyard chickens who likely aren't aware of this.

[1] https://www.who.int/news-room/fact-sheets/detail/lead-poison...

[2] https://extension.oregonstate.edu/gardening/soil-compost/sho...

snickerbockers• 4 years ago

its more fair to say that food cultivated by professional farms who are held to strict safety standards is safer than food cultivated by you in your backyard that was never zoned for mass agriculture. IIRC, Michelle Obama even had some sort of community-garden project where she was growing vegetables on the White House lawn and giving it to local poor people but she had to quit after it was found out that they had toxic chemicals in them.

nonrandomstring• 4 years ago

food cultivated by you in your backyard that was never zoned for mass agriculture.

The way you turned that around seems similar to "Free speech zones".

So now we need official "Health Zones" where children can play safely and ordinary people can grow food as they've done for 12,000 years?

Urban soil is poisoned in Australia. Let's not make excuses or try to hide behind fancy interpretations.

300bps• 4 years ago

Wow, you apparently recall correctly:

https://www.theguardian.com/world/2009/jul/02/michelle-obama...

eatonphil• 4 years ago

Dumb question: is replacing the soil not an option? Too expensive? But surely that's amortized quickly over the term you use the garden? Or maybe you can't fully replace it because the soil is permeable and the lead comes from somewhere else (lower in the ground, rain, etc.)?

hombre_fatal• 4 years ago

Seems pretty notable that everything is so polluted that people can't have chickens nor grow some backyard tubers without heavy lead ingestion.

I think it is news to most people that they should have to care about "zones" just to safely grow a garden. Almost seems like you're saying it's their fault.

selfhoster113• 4 years ago

I'm sorry, but why exactly should the production of food be professionalised? A far better outcome it seems, would be to make sure that everywhere people live is non-toxic enough that food can be grown safely.

rstuart4133• 4 years ago

a more appropriate title for the article would be "urban Australia is so lead-polluted that gardening and raising chickens shows lead poisoning".

As an Australian resident of one of the cities mentioned in the article who has three chooks we keep for eggs, my take would be a little different. I had trouble squaring these statements in the article:

The average level of lead in eggs from the backyard chickens in our study was 301µg/kg. .... Some 51% of the eggs we analysed exceeded the 100µg/kg “food safety” threshold. To keep egg lead below 100μg/kg, our modelling of the relationship between lead in soil, chickens and eggs showed soil lead needs to be under 117mg/kg.

with the maps. How did they get an average of 301ug/kg when most of the area covered by the maps were below the safe level?

Naturally I looked very closely at the maps to see if my suburb was in a high lead area. It wasn't included by the maps at all, so I looked for a pattern I could extrapolate from. Only the inner suburbs were above the 117mg/kg level. My house is a long way away from an inner suburb.

Why the inner suburbs? The article hints at one reason - houses painted with lead paint. Another one sprang to mind - areas with high vehicle density when lead petrol was a thing, but the areas are so small the paint explanation seems a better fit. In Australia, most lead paint ceased to be sold in 1970.

In comparison, Wikipedia says the USA dropped lead paint in 1997, EU formally banned lead paint 2003 (but phase outs happened much earlier in most places, eg UK in 1980), India in 2016.

It's probably obvious to most Australian's, but those maps are misleading for another reason. Australian cities are huge and those maps only cover a small faction of where people live. If indeed it is only the very inner suburbs that are effected, it really is a small portion. Add to that backyards aren't a thing in the CBD, let alone backyard egg laying chooks, and I doubt too many people are effected. That said, I suspect the article has put all egg laying chooks in Mount Isa in mortal danger.

edmcnulty101• 4 years ago

I'd be curious to have a lab test your eggs and see how poor this reporting is.

michaelmior• 4 years ago

How did they get an average of 301ug/kg when most of the area covered by the maps were below the safe level?

Presumably outliers with much higher concentration.

throwaway0a5e• 4 years ago

117mg/kg

God forbid the authors spend 60sec to transform the unit into something that is easily visualize-able to the general public. That should be SOP when writing and editing these kinds of press releases.

Density of typical soil is around 1250kg/m^3 so 117mg/kg is ~146g/m^3. Density of lead is 1.34g/cm&^3 so ~146g/m^3 is 110cm^3 or roughly the size of a small container of cough syrup or 3-4 decent sized fishing weights per cubic meter of soil. That's a lot of lead but probably readily attainable under certain circumstances.

shultays• 4 years ago

  roughly the size of a small container of cough syrup or 3-4 decent sized fishing weights per cubic meter of soil

This does not mean anything to general public either thou. Is it high? Low? How high?

The article says it should be 117mg/kg while guideline is 300mg/kg. Which is pretty clear to me.

ccbccccbbcccbb• 4 years ago

Translating this from agendese to plain English:

We don't want backyard producers to compete with any of our product lines.

We want to feed the population with what we deem healthy for them, and prevent them from deviating from our approved diet.

g8oz• 4 years ago

Looking at the actual numbers it seems like the suburbs are a safe enough place to raise the chickens compared to the older inner core of these Australian cities.

norwalkbear• 4 years ago

Get a lead test for your backyards then, and raise your chickens with peace of mind

photochemsyn• 4 years ago

Mushrooms found growing anywhere near cities or suburbs should also never be consumed, as they specialize in concentrating heavy metals from soils. The most well-known example is the radioactive mushrooms of Chernobyl, which end up eaten by wild boars in the region (and boars don't stay in one place):

https://www.theverge.com/2017/2/24/14733094/radioactive-pigs...

In cities and suburbs the main problem is likely due to the use of tetraethyl lead additives in gasoline for many decades (~1930s to ~1990s). Downwind of coal plants the mercury and arsenic are more problematic. Add both and some more industry and you end up with heavy metal cocktails that just recirculate endlessly.

If you want to grow foods in cities, there is a solution - raised beds that are separate from the underlying dirt, filled with soil trucked in from rural farms that aren't adjacent to industrial pollution sources. Note also that some 'natural environments' have quite a bit of heavy metals and toxic elements, due to natural weathering from geological outcrops, and some plants in these environments accumulate such metals (nickel, arsenic, etc.).

If you're concerned, sending a sample of your local soil to a testing lab is relatively inexpensive.

the-alchemist• 4 years ago

Mushrooms (to be more specific, only certain species) can be used to clean up dirty sites, since they absorb heavy metals so well.

+1 for raised beds.

+1 for testing. Here in the US, almost every college has a Cooperative Extension, and does soil testing. At Rutgers [1], it's just an extra $18 for lead testing.

[1] https://njaes.rutgers.edu/soil-testing-lab/services-fees.php

anonymous344• 4 years ago

1. Lead is known to cause certain illnesses, for example cancer / kidney... ? 2. Now wow does the statistic looks like on a massive dataset for group of people eating more eggs than a median, have they got these diseases ???

yes: study has a valid point no: ignore the study, nobody keeps hens in the suburbs & small yard

jefftk4• 4 years ago

The study isn't saying that this is a reason to avoid eggs in general, they're saying this is a reason to consider stopping eating eggs from urban backyard chickens.

caf• 4 years ago

Or at least get your soil tested.

mercy_dude• 4 years ago

That makes me wonder - does human sperm or eggs show signs of lead poison as well? Has there been any studies on that?

simonsarris• 4 years ago

Insanely disingenuous to conflate "55 Sydney urban gardens" with "backyard" hens. This should be flagged.

TrispusAttucks• 4 years ago

Title could add "in urban Australia" to dissuade the idea that sustainable backyard chickens as a whole are a threat to public health.

dijon-concord• 4 years ago

Are there any known examples where evolution has produced a solution to a problem like this? I've heard of humans adapting to Malaria and lactose consumption in adulthood.

Also, are there any organisms that don't experience lead as a toxic substance, at least in the way that humans do? That might point to adaptation plausibility.

churnedgodotdev• 4 years ago

Since many HN'ers live in the greater Seattle area, it's important to be aware of the Tacoma Smelter Plume:

https://ecology.wa.gov/Spills-Cleanup/Contamination-cleanup/...

For almost 100 years, the Asarco Company operated a copper smelter in Tacoma. Air pollution from the smelter settled on the surface soil of more than 1,000 square miles of the Puget Sound basin. Arsenic, lead, and other heavy metals are still in the soil as a result of this pollution.

infinite8s• 4 years ago

And for anyone in the East side of Toronto, there used to be a lead smelter that polluted the whole neighborhood - http://laurajones.ca/wp/?p=515

albatross13• 4 years ago

noooo you can't just be self sufficient and have your own food, IT'S POISON buy ours instead

Nah, fuck you. I'll eat my lead eggs, thanks.

Backyard hens’ eggs contain 40 times more lead on average than shop eggs

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